Beyond Classical Coordination Chemistry: The First Case of a Triply Bridging Phosphine Ligand

Abstract

Abstract The first example of a triply bridging (μ 3 ‐P) phosphine ligand has been discovered in the crown‐shaped [Cu 3 (μ 2 ‐Hal) 3 L] (Hal=Cl, Br, or I) complexes supported by tris[2‐(2‐pyridyl)ethyl]phosphine (L). Theoretical analysis completely confirms the observed μ 3 ‐P‐bridging pattern, revealing the interaction of the same lone pair of phosphorus with three valence 4s‐orbitals of Cu atoms. The presented complexes exhibit outstanding blue phosphorescence ( λ em =442–465 nm) with the quantum efficiency reaching 100 %. The complex [Cu 3 (μ 2 ‐I) 3 L] also exhibits remarkable thermo‐ and mechanochromic luminescence resulting in a sharp change in the emission colour upon external stimuli. These findings essentially contribute to coordination chemistry of the pnictine ligands.